Children driven to and from school by their parents not only get less exercise than their walking and biking classmates, but also are more inclined to have another unhealthy habit – buying junk food. That's according to new Michigan State University research.

The study, co-led by MSU College of Human Medicine public health researcher Rick Sadler, used GPS technology to track how often and how long 654 students between the ages of 9 and 13 were exposed to fast-food restaurants and convenience stores during their school commutes in the London, Ontario area. Students were also given diaries to record their purchases.

The findings, published in a recent issue of the Canadian Journal of Public Health, showed that the longer the children were exposed to these junk food places when traveling by car (within 50 meters of a GPS track), the more likely they were to make a purchase.

According to Sadler, who worked with co-author Jason Gilliland, a professor at the University of Western Ontario, one message is clear – the person at the wheel, most often a parent, can either turn in at the drive-thru or steer their children toward healthier choices.

Results showed that girls were up to three times more likely than boys to buy junk food. Findings also showed that the rate of fast-food purchases was even higher for students, regardless of gender, who were driven. Compared with their walking and biking classmates, the students who rode in cars were 2.7 times more likely to make a purchase when they were exposed to junk food outlets for five minutes and 4.4 times more likely when exposed for 15 minutes. Those who rode a bus between home and school had less of an opportunity to buy junk food, since these children could only reach these outlets between their bus stop and their home or school.

Sadler said that children on their own, whether walking or biking, are probably less likely to have money to spend on junk food. Yet for parents, often at the end of a workday, it can be easier to give in and buy the junk food than to prepare a healthier meal at home, he added.

“I was a kid like that,” Sadler said. “My parents sometimes did the same thing. Everybody makes these kinds of decisions when in a time crunch.”

One of the reasons the rate of junk food consumption is much higher for children in the United States is likely because about half the students in the London, Ontario area walk or bike to school compared with only 13 percent in the U.S., he said.

“American kids are more likely to be eating junk food,” Sadler said. “If we were to do this study in the U.S., there’d be such a massive contrast.”

The United States also has fewer regulations than Canada on where junk food outlets can be located, such as in proximity to schools, he said.

According to Sadler, educating children and parents about the benefits of healthier eating is not enough because other factors are at play. Particularly in the U.S., a more attractive solution is to “incentivize healthy food rather than demonize unhealthy food,” he said.

“Kids tend to know what they’re supposed to eat. Even when we know what the healthy choices are, there are cues in our environment that steer us into making unhealthy decisions.”

Sadler added that urban planners can reduce the rate of junk food consumption by restricting where the outlets are located, limiting the number of drive-thrus and setting limits on the size of signs.

“There are long-term implications of having this kind of system where you have such easy access to junk food,” he said. “If we want to get serious about public health, we need to recognize the power of planning interventions to drive healthier behaviors by making our cities better places to live.”

Michigan State University public health researcher, Rick Sadler, has been mapping out cities that have had almost no access to healthier food options and evaluating solutions that could help remedy the problem. Photo: Harley J. Seeley